Slack has become a quintessential tool for small and medium sized teams. It provides some powerful integrations and features. At the moment, to stay productive on Slack, there are just 2 keyboard shortcuts I commonly use:

• CMD + <numerical number> - Switch to specified channel
• CMD + K - Opens jump to dialog box. For jumping to channels, people, files and more

Other useful keys:

• Hold CMD - Enumerates your various slack channels.
• CMD + SHIFT + K - Create new direct message (DM) including to multiple people.